This invention relates to a method of securely attaching a plate, such as an anti-rotation plate or flag, to a metal rod, such as a bolt or stud.
Anti-rotation retainers or flags are typically attached to a flange head bolt by staking the corners of the bolt head. Anti-rotation retainers or flags are used in many mass production applications, including automotive applications, to prevent rotation of a bolt during threading of a nut on the threaded end of the bolt using a power wrench. The bolt 20 typically includes a shank portion 22, which may be threaded as shown in FIG. 1 at 24. The bolt also includes an integral radial flange portion 26 and a polygonal head 28. The anti-rotation retainer or flag 30 typically includes a polygonal opening 32 configured to receive the polygonal head 28 of the bolt and the corners of the bolt head are staked, forming small integral projections 34 which overlie the plate 30. That is, the corners of the polygonal head 28 of the bolt are shaved from the free end 29 of the bolt toward the plate 30 and the small projections 34 retain the plate to the bolt.
However, there has been a longstanding problem with this method of securement. The projections 34 are relatively fragile because only the portion of the projections adjacent the plate is integral with the bolt head 28. These projections 34 often break during staking and during handling prior to and during assembly of the bolt in its final application, such as the assembly of a vehicle suspension control arm.
As stated above, the purpose of the anti-rotation retainer or flag is to prevent rotation of the bolt during threading of a nut (not shown) on the bolt using a power wrench. The anti-rotation retainer or flag 30 serves as a wrench during assembly of a nut on the bolt. The flag 30 may include a bent tab 36 which is received between the components of the assembly or in a hole provided in one of the components to be assembled. Thus, the anti-rotation retainer or flag eliminates the requirement of someone holding the bolt with a wrench as a nut is threaded onto the threaded end 24 of the bolt.
For this reason, bolts having an anti-rotation retainer are used extensively by many industries, including the automotive industry, to reduce labor costs during assembly.
However, as stated above, the small staked projections 34 often break off and the anti-rotation retainers become loose or commonly fall off prior to and during assembly of the bolt in its final application. The bolt is then useless where an anti-rotation means is required and discarded. Thus, there has been a longstanding need for a method of securely attaching a plate, such as an anti-rotation retainer, to the head of a flanged bolt which eliminates the problems associated with external staking of the bolt head to the plate by the present method(s).
The method of securely attaching a plate, such as an anti-rotation retainer or flag, to a rod, such as a conventional flange head bolt, of this invention eliminates the problems associated with conventional staking. The resultant rod and plate assembly of this invention is generally stronger than the plate. That is, the push-off force required to remove the plate from the bolt head is generally stronger than the plate, eliminating the problems associated with the prior art described above.
The method of attaching a plate to a malleable metal rod of this invention includes forming an integral annular projection on the head of the rod or flange head bolt. The annular projection is preferably polygonal and most preferably includes a central recess surrounded by a polygonal annular wall. The method then includes forming an opening through the plate configured to receive the integral annular projection on the rod, inserting the annular projection of the rod through the opening in the plate, and permanently deforming the annular projection on the rod radially outwardly to overlie and preferably contact the plate at a plurality of spaced locations, permanently attaching the plate to the rod.
In the most preferred embodiment of the method of attaching a plate to a rod of this invention, the method includes deforming the polygonal annular projection on the rod at the corners of the polygonal projection using a die member having a plurality of spaced radial projections which engage the internal surfaces of the corner portions of the polygonal annular wall radially outwardly to overlie and contact the plate forming a very secure assembly. In the most preferred method of this invention, the die member includes a plurality of spaced generally conical projections angling downwardly from the axis of the die member which deform an inside surface of the annular projection radially outwardly at an angle relative to the axis of the rod, forming a plurality of integral ribs which angle outwardly to overlie and preferably contact the plate.
The rod and plate assembly of this invention therefore includes a rod having a radial flange portion, a head portion and an integral annular polygonal projection having polygonal side walls surrounding a central recess or pocket which extends from the flange portion, a plate having a polygonal opening therethrough which is received on the polygonal projection, and the integral polygonal projection is deformed radially outwardly to overlie and preferably contact the plate at a plurality of spaced locations, preferably at the corners of the polygonal projection. In the most preferred embodiment, the projections extend radially at an angle relative to the axis of the rod, most preferably at an acute angle.
The method of securely attaching a plate to a metal rod and rod and plate assembly of this invention thus solves the problems associated with the prior method of staking described above, eliminating loss of anti-rotation retainers and thereby reducing cost. Further, the size of the bolt head may be reduced, reducing the weight of the assembly and cost. Finally, the plate and rod assembly of this invention reduces manufacturing cost as discussed further below.